Basic

• Key-value storage
• In memory, single threaded, written in C
• Data types supported
  • Strings
  • Hashes (Objects)
  • Lists
  • Sets
  • Sorted Sets (Priority Queues)
  • Bloom Filters
  • Geospatial Indexes
  • Time Series
• Can be single node, replicated or in clusters (load balancer to schedule the load to different nodes)

Design Redis

capabilities

• cache
  • distribute the hash map across nodes, simplifies scaling process
  • TTL is used for eviction, never reads value of key that has expired
  • Hot Key Problem
• As distributed lock
  • use INCR to represent lock